反转字符串中的所有其他单词，保持标点符号Swift

Question

所以我陷入了一个我几乎也知道答案的编码挑战。而且我认为我必须使用 Swift 4 中的 subString 调用来获得 100%。我想反转字符串中的每个其他单词，但忽略或将标点符号保留在其原始位置（索引）。

var sample = "lets start. And not worry about proper sentences."

func reverseString(inputString: String) -> String {
    let oldSentence = sample.components(separatedBy: " ")
    var newSentence = ""
    for index in 0...oldSentence.count - 1 {
        let word = oldSentence[index]
        if newSentence != "" {
            newSentence += " "
        }
        if index % 2 == 1 {
            let reverseWord = String(word.reversed())
            newSentence += reverseWord
        } else {
            newSentence += word
        }
    }
    return newSentence
}

reverseString(inputString: sample)

这将是预期的输出。

"lets trats. And ton worry tuoba proper secnetnes."

注意标点没有颠倒。

Answer 1

您不应使用components(separatedBy: ) 将字符串拆分为单词。原因见this article。使用enumerateSubstrings 并传入适当的选项：

func reverseString(inputString: String) -> String {
    var index = 1
    var newSentence = inputString
    inputString.enumerateSubstrings(in: inputString.startIndex..., options: .byWords) { substr, range, _, stop in
        guard let substr = substr else { return }
        if index % 2 == 0 {
            newSentence = newSentence.replacingCharacters(in: range, with: String(substr.reversed()))
        }
        index += 1
    }
    return newSentence
}

print(reverseString(inputString: "lets start. And not worry about proper sentences."))
// lets trats. And ton worry tuoba proper secnetnes.

print(reverseString(inputString: "I think, therefore I'm"))
// I kniht, therefore m'I